9 Volt Batteries

What is the intended use for the battery?  Li-Ion is great for some things, and not so great of others.  Also keep in mind that Li-ion batteries need to be charged on a charger designed for them.  They will be damaged if charged on a charger made only for NiCD/NiMH batteries.  

On the mAh ratings, the term is pretty straight forward on the surface.  the number is how many amps (milliamps) of current the battery will supply for one hour.  You can work the math from there, for example, if your battery is rated for 1000mAh, you get 1 amp for an hour, or 2 amps for half an hour, or a tenth of an amp for 10 hours.  Where things get tricky comes in two ways.  First many off brand battery manufacturers over rate their batteries, and they don't live up to the stated capacity.  this is especially true if you see uncommonly high ratings well above what the name brand batteries offer.  The second issue is the rate of discharge.  Depending on what you are using the battery for this may or may not be a problem, but it comes up for folks running high power RC cars and planes.   While a battery may be rated for , say, 1500 mAh, it may not actually be able to deliver 1.5 amps for an hour. it may only be able to provide 500 mA of current to the device, but do so for 3 hours.  If your device requires high current for short periods of time, this is something you'll have to watch out for, and find a battery designed for high discharge rates.  

So on your question of 1000mA vs 600 mAh they are likely apples and oranges.  one is the maximum discharge rate, and the other is the total capacity of the battery.  you actually need both numbers to make an informed decision.  

As far as the chargeable/non chargeable, these are two different things for practical purposes.  they use the same technology to create power, but put together in a slightly different way.  If it's for a smoke alarm the non-chargable sort is what you want.  for anything else you probably will be better off with a chargeable battery.  

Depending on the application, NiMH, or NiCD may be better choices as well, so don't count them out... 

We'll finish where we started, What is the intended use for the battery? 

JGL

Thanks John.  I am converting some passenger cars to LED, battery powered lighting.  Gets rid go the center rail pick up rollers and the axle wipers.  Plus it allows constant lighting without the need for a capacitor.  And most importantly, it's simple.  I usually use straight forward 9 volt batteries like Duracell or Energizer.  All of my large scale stuff that has lighting uses the system I described.  The batteries last forever.  I was just thinking if going to Li-on rechargeables was worth the expense.

if you get rid of pick ups I will take them,

While I tend to like track power, the battery is pretty simple.  

I would compare costs and capacity between using various types of batteries, both sizes and chemical types.  

For your purpose, the 9v battery is really simple, but using AA size batteries may be much more cost effective in the long run.  AA's are also easier to properly charge, and depending on your wiring scheme may be easier to get the correct voltage for your LEDs.  

On the chemistry, Li-ion tend to have higher capacities than other types of rechargeable batteries, however NiMH are typically less expensive, and do not require a specialized charger.  Li-ion batteries require a charger specifically designed to charge them that can properly monitor the current draw and voltage of the cells, and with 9v types this is particularly difficult to do correctly as the charger can not monitor individual cells of the battery.  NiMH are much easier to charge and any overnight type battery charger will do an adequate job with them.  Specialized chargers are still better, but not needed.  

For your purpose of powering LEDs, the discharge rate won't matter much, if at all.  Capacity will be more important.  To compare a Duracell coper top 9v battery will supply between 90 and 310 mAh of current, varying depending on the draw.  310 mAh at 100mA draw, 90 mAh at 1 amp draw.   I expect the lighting for a single car is somewhere in the 50-100 mA range, but that will vary based on how you wire things.  Point of all this is, you can probably assume a typical high quality alkaline battery will provide about 300mAh of power, and can use that to compare for run time with NiMH batteries with about 2/3 of that capacity, or Li-Ion types with about twice that capacity to determining how often you will have to charge the various types, and if the investment in Li-Ion batteries and the charger for them is worthwhile or not for you.  

There are also odd-ball battery choices out there that are becoming more common place these days such as the 18650 type battery.  These look something like a jumbo sized AA battery and are 3.6 volt batteries that provide 1800-3000 mAh of current.  While not quite as cost effective as AA or AAA types the 18650, or smaller 18350 are nice choices if a 3.6v supply makes sense.  

With the NiMH type you also have 2 choices there.  There are 'standard' or High Self-Discharge types, and Low Self-Discharge (often marked Pre-Charged).  Depending on your usage one may be a better choice than the other.  The LSD type will hold a charge for at least a year, often 18-24 months, but they have a smaller capacity.  The standard types have a higher capacity, but are lucky to hold the charge for a month, often less than that.  

I'm not really mentioning NiCD type batteries because these are no longer common place, tend to be more expensive than NiMH, and have smaller capacities.  With one exception, NiMH out performs NiCD in every way.  The one exception being that NiCD batteries will last for 2 to 3 times as many charge cycles... if properly maintained... On the other hand, the capacity of NiMH batteries is often twice as high, so you won't have to charge it as many times to provide the same amount of run time.  Cadmium is also rather toxic so disposing of NiCD batteries has become a bit of an issue. 

When it comes to personal experience I find Li-Ion and NiMH equally reliable when charged properly.  My cameras use 7.2 volt Li-Ion battery packs and have an equal number of charge cycles to my AA NiMH batteries used in my flashes, several hundred charge cycles on each over 5+ years.  I have some examples of each still working properly that are much older, but I do not know how many charges they have seen.  I only keep records on my main camera, not the 3-4 dozen other cameras and hundreds of batteries we use in the company.  When it comes to NiMH, I prefer Duracell over all other brands, but will also go for Rayovac if Duracell is not available.  Random off brands are hit or miss, with the ones offering lower mAh ratings typically being of better quality, while those claiming really high ratings, well above those of the name brands tend to be garbage.  I find the bunny brand to be somewhere between barely usable and garbage.  

Aren't you glad you asked about batteries?  

JohnGaltLine posted:

While I tend to like track power, the battery is pretty simple.  

I would compare costs and capacity between using various types of batteries, both sizes and chemical types.  

For your purpose, the 9v battery is really simple, but using AA size batteries may be much more cost effective in the long run.  AA's are also easier to properly charge, and depending on your wiring scheme may be easier to get the correct voltage for your LEDs.  

On the chemistry, Li-ion tend to have higher capacities than other types of rechargeable batteries, however NiMH are typically less expensive, and do not require a specialized charger.  Li-ion batteries require a charger specifically designed to charge them that can properly monitor the current draw and voltage of the cells, and with 9v types this is particularly difficult to do correctly as the charger can not monitor individual cells of the battery.  NiMH are much easier to charge and any overnight type battery charger will do an adequate job with them.  Specialized chargers are still better, but not needed.  

For your purpose of powering LEDs, the discharge rate won't matter much, if at all.  Capacity will be more important.  To compare a Duracell coper top 9v battery will supply between 90 and 310 mAh of current, varying depending on the draw.  310 mAh at 100mA draw, 90 mAh at 1 amp draw.   I expect the lighting for a single car is somewhere in the 50-100 mA range, but that will vary based on how you wire things.  Point of all this is, you can probably assume a typical high quality alkaline battery will provide about 300mAh of power, and can use that to compare for run time with NiMH batteries with about 2/3 of that capacity, or Li-Ion types with about twice that capacity to determining how often you will have to charge the various types, and if the investment in Li-Ion batteries and the charger for them is worthwhile or not for you.  

There are also odd-ball battery choices out there that are becoming more common place these days such as the 18650 type battery.  These look something like a jumbo sized AA battery and are 3.6 volt batteries that provide 1800-3000 mAh of current.  While not quite as cost effective as AA or AAA types the 18650, or smaller 18350 are nice choices if a 3.6v supply makes sense.  

With the NiMH type you also have 2 choices there.  There are 'standard' or High Self-Discharge types, and Low Self-Discharge (often marked Pre-Charged).  Depending on your usage one may be a better choice than the other.  The LSD type will hold a charge for at least a year, often 18-24 months, but they have a smaller capacity.  The standard types have a higher capacity, but are lucky to hold the charge for a month, often less than that.  

I'm not really mentioning NiCD type batteries because these are no longer common place, tend to be more expensive than NiMH, and have smaller capacities.  With one exception, NiMH out performs NiCD in every way.  The one exception being that NiCD batteries will last for 2 to 3 times as many charge cycles... if properly maintained... On the other hand, the capacity of NiMH batteries is often twice as high, so you won't have to charge it as many times to provide the same amount of run time.  Cadmium is also rather toxic so disposing of NiCD batteries has become a bit of an issue. 

When it comes to personal experience I find Li-Ion and NiMH equally reliable when charged properly.  My cameras use 7.2 volt Li-Ion battery packs and have an equal number of charge cycles to my AA NiMH batteries used in my flashes, several hundred charge cycles on each over 5+ years.  I have some examples of each still working properly that are much older, but I do not know how many charges they have seen.  I only keep records on my main camera, not the 3-4 dozen other cameras and hundreds of batteries we use in the company.  When it comes to NiMH, I prefer Duracell over all other brands, but will also go for Rayovac if Duracell is not available.  Random off brands are hit or miss, with the ones offering lower mAh ratings typically being of better quality, while those claiming really high ratings, well above those of the name brands tend to be garbage.  I find the bunny brand to be somewhere between barely usable and garbage.  

Aren't you glad you asked about batteries?  

John,

Even though your response was very informative. I think my brain went it to overload.

Sorry, I tend to produce word vomit from time to time when I get going on something.

JGL 

riki posted:

if you get rid of pick ups I will take them,

You are welcomed to them.  I did not remove the pick-up holder from the truck frame however.  It's just the roller and it's own frame that snaps into the truck frame.  Send me a message.  My email address in on my profile page.